Adam has a total of 14 ducks and sheep.
The difference in their number of legs is 4.
How many (a) sheep and (b) ducks does Adam have?
Number of ducks |
Number of ducks' legs |
Number of sheep |
Number of sheep' legs |
Difference in the number of legs |
14 |
14 x 2 = 28 |
0 |
0 x 4 = 4 |
28 - 0 = 28 |
13 |
13 x 2 = 26 |
1 |
1 x 4 = 4 |
26 - 4 = 22 |
10 |
10 x 2 = 20 |
4 |
10 x 4 = 16 |
20 - 16 = 4 |
If all of the animals are ducks,
the number of legs needed
= 14 x 2
= 28
Total difference in the number of legs
= 28 - 4
= 24
Difference in the number of legs when 1 duck is replaced by 1 sheep
= 28 - 22
= 6
Number of sheep
= 24 ÷ 6
= 4 (a)
Number of ducks
= 14 - 4
= 10 (b)
Answer(s): (a) 4; (b) 10